I've acquired a Datel RF302R external floppy, but it is missing a PSU and I was wondering if anybody here might have one that they could check for me, to see what the output output rating (Volts & Amps) is for the PSU.

It looks like the voltage regulator onboard does take a wide variety of voltages (Something like 9v to 24v), and I do get 5v when I feed it 9v, but I'm not convinced it has enough power, as the drive simply isn't recognised on any of my STs.

I'll have a dig in the meantime and see what other spare PSUs I have and maybe try 12v, but if anybody does have any info I'd be grateful.

So seems my memory is going, I was using a 12v/1A supply, which as it turns out was more than enough for what I wanted, as it looks like it's the floppy drive that was at fault.

Having dug out a number of spare drives last night, and confirmed the orientation of the plug (It's not keyed), I discovered a few things.

1. The drive that came in the enclosure doesn't seem to work. I have about 4 other drives that will work in this case though.
2. The cable, which goes straight through from the plug to the drive must effectively contain a twist in it, since the external drive has to be set to DS0 or it doesn't work. I will have to look a this more to confirm.
3. Gotek drives don't seem to work in this configuration, even set to DS0, however this needs more work as there are other jumper options on the Gotek that can be examined.

So I have spare floppy drives that will work with this enclosure. Some are 1.44Mb drives converted to DS0, others are original ST drives, so I can get it back up and running.

Next thing to consider is if it will work with my 520ST as a single drive, as if point 2 is true, it means the enclosure uses cable select, so the ST may see it as drive B:

I thought internal was set to DS0, have I got this mixed up? Should the internal drive be set to DS1?

No wait, internal should be DS0, that's how my Goteks are set up on all my STs.

In the working scenario I had last night, I had a 1040 STF set up with the external drive set as DS0 and the internal drive, and assuming that is set to DS0 too, then that suggests a cable twist in the external cable surely?

I had to check my MPF image to check, Internal on the ST is DS0. So external should be DS1.

I don't know of the external drive you are using. But maybe its just wired up as a different drive select line by default ? I would check the ST floppy connector end, DS1 and DS0 are on there.. I'm assuming if you swap them in the connector, then it should all work how it should then.

The ST is designed so that all drives, internal and external, should be configured as DS0. Due to the internal wiring, an external drive configured as DS0 will be seen as DS1 by the computer.

If the drive can't be configured as DS0 (Gotek certainly can), then you need to switch the signals somehow by yourself.

Note that there are two completely different types of cable twisting. One is that for a non Atari drive mechanism, including Gotek of course, the whole cable must be twisted. The IDE connector is reversed. This is unrelated to twisting the drive select/motor signals to swap DS0 with DS1.